Linux kernel mirror (for testing)
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linux
1/*
2 * linux/include/asm-arm/byteorder.h
3 *
4 * ARM Endian-ness. In little endian mode, the data bus is connected such
5 * that byte accesses appear as:
6 * 0 = d0...d7, 1 = d8...d15, 2 = d16...d23, 3 = d24...d31
7 * and word accesses (data or instruction) appear as:
8 * d0...d31
9 *
10 * When in big endian mode, byte accesses appear as:
11 * 0 = d24...d31, 1 = d16...d23, 2 = d8...d15, 3 = d0...d7
12 * and word accesses (data or instruction) appear as:
13 * d0...d31
14 */
15#ifndef __ASM_ARM_BYTEORDER_H
16#define __ASM_ARM_BYTEORDER_H
17
18#include <linux/compiler.h>
19#include <asm/types.h>
20
21static inline __attribute_const__ __u32 ___arch__swab32(__u32 x)
22{
23 __u32 t;
24
25 if (__builtin_constant_p(x)) {
26 t = x ^ ((x << 16) | (x >> 16)); /* eor r1,r0,r0,ror #16 */
27 } else {
28 /*
29 * The compiler needs a bit of a hint here to always do the
30 * right thing and not screw it up to different degrees
31 * depending on the gcc version.
32 */
33 asm ("eor\t%0, %1, %1, ror #16" : "=r" (t) : "r" (x));
34 }
35 x = (x << 24) | (x >> 8); /* mov r0,r0,ror #8 */
36 t &= ~0x00FF0000; /* bic r1,r1,#0x00FF0000 */
37 x ^= (t >> 8); /* eor r0,r0,r1,lsr #8 */
38
39 return x;
40}
41
42#define __arch__swab32(x) ___arch__swab32(x)
43
44#if !defined(__STRICT_ANSI__) || defined(__KERNEL__)
45# define __BYTEORDER_HAS_U64__
46# define __SWAB_64_THRU_32__
47#endif
48
49#ifdef __ARMEB__
50#include <linux/byteorder/big_endian.h>
51#else
52#include <linux/byteorder/little_endian.h>
53#endif
54
55#endif
56